The point of Haskells type system though is that those annotations tell you most if not all of those things, they're a form of documentation that is very powerf

The point of Haskells type system though is that those annotations tell you most if not all of those things, they're a form of documentation that is very powerful and designing your types clearly makes it even better. Plus your annotations are updated! Comments wither and die. [Edit] to be clear, if there is something going on that would cumbersome to "document with types" i just write comments. There's also a place for function description and example.